1. (proper noun) Thrash metal pit fare born of New Jersey. The first thrash metal band in the history of metal, forming in 1980 and releasing classic thrash metal albums such as The Years of Decay, WFO and Horrorscope.

2. (proper noun) A Motorhead album and its title track where the band of this name got it from.

3. (noun) The act, or acts, of doing more than what is necessary to accomplish a task. Often associated with warfare.

1. I saw Overkill play last night and they played a kickass show.
2. A 112,000 square foot Wal-Mart is overkill for this small town.

2. A very fast motorhead song from 1979, It has the most badass drum into of any song... ever. Incidently, the drum intro was said to be "Overkill" as per the first definition by Motorhead's Bass Player / Singer Lemmy Kilmister.

1. Using a sledgehammer to swat a fly on your friends nose.

2.
Only way to feel the noise is when it's good and loud,
So good you can't believe it's screaming with the crowd,
Don't sweat it, get it back to you,
Overkill! Overkill! Overkill!